Fig. 2

Scheme showing the mechanism of action of the fluorescent sensor for sequence-specific recognition of the target DNA. In the absence of the targeted RNA virus, this molecular beacon virus probe was in a “Signal off” state in which the fluorescence of the recognition strand was quenched due to fluorescence resonance energy transfer between the fluorophore (FAM) and the quencher (BHQ2). In the presence of RNA virus, it will competitively bind to the recognizing targeted virus nucleic acid and result in the release of the complementary strand, to induce the ‘‘Signal on’’ state of the fluorescence